System Reliability Analysis Method Based on T-S FTA and HE-BN

For high-reliability systems in military,aerospace,and railway fields,the challenges of reliability analysis lie in dealing with unclear failure mechanisms,complex fault relationships,lack of fault data,and uncertainty of fault states.To overcome these problems,this paper proposes a reliability analysismethod based on T-S fault tree analysis(T-S FTA)and Hyper-ellipsoidal Bayesian network(HE-BN).The method describes the connection between the various systemfault events by T-S fuzzy gates and translates them into a Bayesian network(BN)model.Combining the advantages of T-S fault tree modeling with the advantages of Bayesian network computation,a reliability modeling method is proposed that can fully reflect the fault characteristics of complex systems.Experts describe the degree of failure of the event in the form of interval numbers.The knowledge and experience of experts are fused with the D-S evidence theory to obtain the initial failure probability interval of the BN root node.Then,the Hyper-ellipsoidal model(HM)constrains the initial failure probability interval and constructs a HE-BN for the system.A reliability analysismethod is proposed to solve the problem of insufficient failure data and uncertainty in the degree of failure.The failure probability of the system is further calculated and the key components that affect the system’s reliability are identified.The proposedmethod accounts for the uncertainty and incompleteness of the failure data in complex multi-state systems and establishes an easily computable reliability model that fully reflects the characteristics of complex faults and accurately identifies system weaknesses.The feasibility and accuracy of the method are further verified by conducting case studies.

Structural Interval Reliability Algorithm Based on Bernstein Polynomials and Evidence Theory

Structural reliability is an important method to measure the safety performance of structures under the influence of uncertain factors.Traditional structural reliability analysis methods often convert the limit state function to the polynomial form to measure whether the structure is invalid.The uncertain parameters mainly exist in the form of intervals.This method requires a lot of calculation and is often difficult to achieve efficiently.In order to solve this problem,this paper proposes an interval variable multivariate polynomial algorithm based on Bernstein polynomials and evidence theory to solve the structural reliability problem with cognitive uncertainty.Based on the non-probabilistic reliability index method,the extreme value of the limit state function is obtained using the properties of Bernstein polynomials,thus avoiding the need for a lot of sampling to solve the reliability analysis problem.The method is applied to numerical examples and engineering applications such as experiments,and the results show that the method has higher computational efficiency and accuracy than the traditional linear approximation method,especially for some reliability problems with higher nonlinearity.Moreover,this method can effectively improve the reliability of results and reduce the cost of calculation in practical engineering problems.

Non-probabilistic fuzzy reliability analysis of pile foundation stability by interval theory

Randomness and fuzziness are among the attributes of the influential factors for stability assessment of pile foundation. According to these two characteristics, the triangular fuzzy number analysis approach was introduced to determine the probability-distributed function of mechanical parameters. Then the functional function of reliability analysis was constructed based on the study of bearing mechanism of pile foundation, and the way to calculate interval values of the functional function was developed by using improved interval-truncation approach and operation rules of interval numbers. Afterwards, the non-probabilistic fuzzy reliability analysis method was applied to assessing the pile foundation, from which a method was presented for non- probabilistic fuzzy reliability analysis of pile foundation stability by interval theory. Finally, the probability distribution curve of non- probabilistic fuzzy reliability indexes of practical pile foundation was concluded. Its failure possibility is 0.91%, which shows that the pile foundation is stable and reliable.

An Improved CREAM Model Based on DS Evidence Theory and DEMATEL

Cognitive Reliability and Error Analysis Method(CREAM)is widely used in human reliability analysis(HRA).It defines nine common performance conditions(CPCs),which represent the factors thatmay affect human reliability and are used to modify the cognitive failure probability(CFP).However,the levels of CPCs are usually determined by domain experts,whichmay be subjective and uncertain.What’smore,the classicCREAMassumes that the CPCs are independent,which is unrealistic.Ignoring the dependence among CPCs will result in repeated calculations of the influence of the CPCs on CFP and lead to unreasonable reliability evaluation.To address the issue of uncertain information modeling and processing,this paper introduces evidence theory to evaluate the CPC levels in specific scenarios.To address the issue of dependence modeling,the Decision-Making Trial and Evaluation Laboratory(DEMATEL)method is used to process the dependence among CPCs and calculate the relative weights of each CPC,thus modifying the multiplier of the CPCs.The detailed process of the proposed method is illustrated in this paper and the CFP estimated by the proposed method is more reasonable.

ON INFORMATION THEORY METHOD FOR RELIABILITY ASSESSMENT OF SYSTEMS CONSISTING OF DIFFERENT SUCCESS FAILURE MODEL UNITS

Using the characteristic of addition of information quantity and the principle of equivalence of information quantity, this paper derives the general conversion formulae of the formation theory method conversion (synthesis) on the systems consisting of different success failure model units. According to the fundamental method of the unit reliability assessment, the general models of system reliability approximate lower limits are given. Finally, this paper analyses the application of the assessment method by examples, the assessment results are neither conservative nor radical and very satisfactory. The assessment method can be popularized to the systems which have fixed reliability structural models.

Improvement method for the combining rule of Dempster-Shaferevidence theory based on reliability

An improvement method for the combining rule of Dempster evidence theory is proposed. Different from Dempster theory, the reliability of evidences isn't identical; and varies with the event. By weight evidence according to their reliability, the effect of unreliable evidence is reduced, and then get the fusion result that is closer to the truth. An example to expand the advantage of this method is given. The example proves that this method is helpful to find a correct result.

Safe range analysis of clear distance of twin shallow tunnels based on limit analysis and reliability theory

A method of analyzing the stability of twin shallow tunnels was presented using both limit analysis with nonlinear failure criterion and reliability theory.In the condition of nonlinear failure criterion,the critical clear distancesof twin shallow tunnels were obtained by analyzing the change of surrounding pressure.A reliability model was established based on limit state equation,and the failure probability was solved by virtue of Monte Carlo method.Safety factor and corresponding clear distance of different safety levels were obtained by introducing a target reliability index.The scope of clear distance for different safety levels is described,which can be used as a supplement and improvement to the design codes of tunnels.

Convex Set Theory for Reliability Assessment of Steel Beam with Bounded Uncertainty

Probabilistic reliability model established by insufficient data is inaccessible. The convex model was applied to model the uncertainties of variables. A new non-probabilistic reliability model was proposed based on the robustness of system to uncertainty. The non-probabilistic reliability model,the infinite norm model,and the probabilistic model were used to assess the reliability of a steel beam,respectively. The results show that the resistance is allowed to couple with the action effect in the non-probabilistic reliability model. Additionally,the non-probabilistic reliability model becomes the same accurate as probabilistic model with the increase of the bounded uncertain information. The model is decided by the available data and information.

Reliability analysis of a composite laminate using estimation theory

Composite laminates are made up of composite single-plies sequence. The plies generally have the same fiber and resin and their difference in fiber orientation results in a difference in various laminates' strength. Tsai-Hill failure criterion as a limiting state function to analyze structural reliability of a composite laminate and estimation theory in order to estimate statistical parameters of effective stress were utilized to construct probability box. Finally, we used the Monte Carlo simulation and FERUM software to calculate the upper and lower bounds of probability of failure.

Fundamental Issues Towards Unified Design Theory of Recycled and Natural Aggregate Concrete Components

In the past 20 years,recycled aggregate concrete(RAC),as a type of low-carbon concrete,has become a worldwide focus of research.However,the design methodology for RAC structural components remains a challenge.Consequently,demands for a unified design of natural aggregate concrete(NAC)and RAC components have been presented.Accordingly,this study analyses the necessity of a unified design theory and provides an in-depth demonstration of the strength determination,compressive constitutive relationship,and design method of concrete components.The coefficient of variation of RAC strength is found to be generally higher than that of NAC strength.The compressive and tensile strengths of RAC can be defined and determined using the same method as that used for NAC.The uniaxial compressive constitutive relationship between NAC and RAC has a unified mathematical expression.However,the elastic modulus of RAC decreases,and its brittleness exhibits an increasing trend compared with that of NAC.Finally,to unify the design formulae of RAC and NAC components for bearing capacity,modification factors for RAC components are proposed considering safety and reliability.Additionally,the feasibility of the proposed unified time-dependent design theory is demonstrated in terms of conceptual design and structural measures considering the effects of strength degradation and reinforcement corrosion.It is believed that this study enriches and develops the basic theory of concrete structures.

Generation Reliability Evaluation in Deregulated Power Systems Using Game Theory and Neural Networks

Deregulation policy has caused some changes in the concepts of power systems reliability assessment and enhancement. In the present research, generation reliability is considered, and a method for its assessment is proposed using Game Theory (GT) and Neural Networks (NN). Also, due to the stochastic behavior of power markets and generators’ forced outages, Monte Carlo Simulation (MCS) is used for reliability evaluation. Generation reliability focuses merely on the interaction between generation complex and load. Therefore, in the research, based on the behavior of players in the market and using GT, two outcomes are considered: cooperation and non-cooperation. The proposed method is assessed on IEEE-Reliability Test System with satisfactory results. Loss of Load Expectation (LOLE) is used as the reliability index and the results show generation reliability in cooperation market is better than non-cooperation outcome.

Research on the reliability of the electromechanical products based on the fuzzy theory

Mechanical and electrical products are more and more widely used in all the fields of the society. With the increase in the degree of automation and miniaturization, the structure of many mechanical and electrical products is becoming more and more complex, and the conditions of the use are also increasingly harsh, and therefore more and more product reliability issues are arising, and the reliability technology is being paid more and more attention to. In this paper, aiming at the mechanical and electtical products, from the three aspects of reliability management, reliability design and analysis, and reliability test and evaluation, the reliability research is preliminary studied.

Research on Preventive Maintenance Strategy of Simulator Based on Reliability Theory

Based on the theory of reliability, this paper studies the preventive maintenance strategy of the simulator with incomplete maintenance, and establishes the preventive maintenance model with the aim of simulating the maintenance cost and simulating machine availability. The main contents of this paper are as follows： Firstly, this paper introduces the background and significance of this paper, expatiates the relevant concepts and mathematical foundation of simulator maintenance related theory and reliability maintenance thought, simulator performance degradation law, Weibull parameter estimation method, As the center of the maintenance （RCM） theory of system maintenance decision analysis.

Reliability analysis of torpedo loading based on fractional-order optimization model

A fractional-order cumulative optimization GM(1,2)model based on grey theory is proposed to study the relationship between torpedo loading and working reliabilities.In this model,the average relative error function related to order and background value is established.Taking the average relative error function as the objective function,the optimal value of the two parameters is obtained through the optimization method,and the minimum value of the average relative error is determined.The calculation example shows that this method can greatly improve the accuracy of the model and more accurately reflect the relationship between torpedo loading and working reliabilities compared with the traditional GM(1,2)model.

Research of Pipeline Pressure Based on the Reliability Theory

The former gas pipeline operating pressure transmission determined mostly according to the determined formula into the corresponding pipeline parameters are obtained, and the parameters of the actual pipeline due to many reasons, such as measurement error, production batch, etc., is not a fixed value. This paper on pipeline integrity established limit state equation, using Monte Carlo method to calculate the gas pipeline in different pressures of reliability, according to the API （American Petroleum Institute） 579 recommended target reliability to determine the operating pressure of the different regions, and design coefficient method, the calculated results are compared, results of calculation reliability is more reasonable and improve the delivery pressure of the area, the pipeline safety management provides the basis.

慢性心力衰竭患者运动康复依从性量表的编制及信效度检验

背景慢性心力衰竭患者运动康复效果的维持有赖于良好的运动康复依从行为,有效及科学地评估其运动康复依从性具有重要的实践意义,但目前国内外尚缺乏公认的慢性心力衰竭患者运动康复依从性评价工具。目的编制慢性心力衰竭患者运动康复依从性量表,为快速便捷地评估慢性心力衰竭患者运动康复依从性提供科学、适宜的工具。方法在前期慢性心力衰竭患者运动康复最佳证据总结和质性研究的基础上,通过文献回顾、结合课题组意见,形成初始条目池;根据小样本预调查、德尔菲专家函询形成临床测试版量表。便利抽样法选取2020年11月—2021年2月在江苏省3所三级甲等医院心血管内科就诊的稳定期慢性心力衰竭患者作为研究对象。第一阶段发放有效量表274份,结合项目反应理论和经典测量理论对量表的条目进行筛选并进行探索性因子分析,形成正式版量表;第二阶段发放有效量表282份,对正式版量表进行验证性因子分析和信效度分析,形成最终版量表。结果正式量表包括2个维度11个条目。各条目的难度合理,且均未出现逆反阈值,条目区分度、项目信息量及项目特征曲线均较优。量表总的Cronbach’sα系数为0.905,其中“处方依从”维度Cronbach’sα系数为0.895,“监测依从”维度Cronbach’sα系数为0.910。总折半信度为0.724、重测信度为0.902。探索性因子分析结果显示2个因子能解释总变异的70.231%,进一步验证性因子分析的结果显示模型各参数较优,拟合较好。结论本研究构建的慢性心力衰竭患者运动康复依从性量表的条目难度、区分度合理,项目信息量较好,同时具有较高的信度和效度,可作为慢性心力衰竭患者运动康复依从性的评估工具。

新生儿科护士早产儿体位支持行为评估量表的编制及信效度检验

目的:编制新生儿科护士早产儿体位支持行为评估量表并验证其信效度。方法:以健康行为改变的多理论模型为指导,通过文献回顾形成新生儿科护士早产儿体位支持行为评估量表初稿,通过专家小组讨论对量表初稿条目进行修订,通过专家函询、预调查形成新生儿科护士早产儿体位支持行为评估量表。采用便利抽样法对203名新生儿重症监护室(NICU)和新生儿科病房临床护士进行测评,检验量表信效度。结果:新生儿科护士早产儿体位支持行为评估量表包括4个维度(体位支持的意义、体位支持的自我努力与社会支持、体位支持的物理环境支持、体位支持的信心),共25个条目。探索性因子分析显示,4个维度的累计方差贡献率为87.143%。量表水平的内容效度指数为0.941。量表总体的Cronbach′s α系数为0.972,折半信度为0.765,重测信度为0.862。结论:新生儿科护士早产儿体位支持行为评估量表具有良好的信效度,可用于护士的早产儿支持行为评估。

基于案例引导的可靠性理论教学模式探析

常规可靠性理论教学存在重视公式推导而轻视案例分析的现状,课程教学效果不佳。文章探索用案例教学法讲授该课程知识,着重强调案例教学理念与编程实践促学的重要性。结合4个典型工程案例,如悬臂梁、海堤、基桩、板桩墙等构筑物,说明可靠性理论教学实施的步骤与方法。每个案例各有侧重,由浅入深地引出重要知识点,通过编程实践引导学生进行实例求解。基于案例启发式的教学模式可激发学生探求可靠性理论的学习热情,从而实现与专业问题相互衔接。

双向地震作用下崩塌堆积体边坡动力模糊可靠性分析

考虑崩塌堆积体边坡岩土体参数随机性和模糊性,以及地震力双向性,建立一种边坡地震动力模糊可靠度计算方法,针对竖向地震力对崩塌堆积体边坡稳定可靠性的影响进行进一步研究。首先,选用动力有限元时程分析法计算出双向地震工况下崩塌堆积体边坡的响应特征,并运用模糊理论对强度参数进行模糊性处理;然后,根据Mohr-Coulumb强度准则构建边坡安全系数与可靠度的时程计算模型;最后,采用边坡地震可靠性评价新方法,通过MATLAB编写相应程序,实现计算和分析结果的快速输出。案例结果表明:新方法计算结果更加合理,对工程而言也更加安全;竖向地震作用均对崩塌堆积体边坡整体可靠性存在影响,但影响程度需根据工程实际情况进行分析。在算例工况下,竖向地震对崩塌堆积体边坡的可靠性影响很小,仅使得可靠度降低3.55%,因此,可仅考虑水平地震的影响。

基于图论的动态调整拓扑限制短路电流措施对系统可靠性影响研究

随着电力系统规模的逐渐扩大和负荷密度的提升,短路电流超标问题逐渐成为制约电网发展的重要因素。基于系统拓扑动态调整的短路电流限制措施,不影响系统正常运行,仅在故障期间调整系统结构,这一措施的引入可能对系统的可靠性造成一定的影响。该文研究了电网连通性的图论建模方法及计算方法,并以典型电网为例建立了系统拓扑仿真算例,分析了不同拓扑调整方法下,短路电流抑制效果和对系统可靠性的影响。结果表明,220kV系统典型接线下,拓扑调整开关配置母线分段开关处可作为首先考虑的方案,其短路电流抑制效果较好,对系统可靠性影响相对较小。